The two-phase thermal transport technology consists of transporting heat from a hot source to a cold sink through cyclical evaporation/condensation processes of a working fluid without any external contribution of energy. A heat transfer device based in this technology is also known as a heat transfer device of a Loop Heat Pipe (LHP) type.
Typically, a Loop Heat Pipe includes a working fluid, an evaporator section and a condenser section. The working fluid is vaporized at the evaporator section (due to the heat source extraction). The vapor is received at the condenser section, whereupon the vapor is condensed to form a liquid working fluid. Capillary action returns the condensed working fluid to the evaporator section, thereby completing a cycle.
LHP type heat transfer devices are being used in spacecraft and computers to cool internal devices. The heat generated by the internal devices is absorbed by the evaporator and released at the condenser, thus allowing the temperature of the internal devices to be controlled. Because no mechanically driven parts are used, the heat transfer devices can be stably used for long periods in unmanned spacecraft and computers.
European Patent Application EP 2 157 391 A1 and U.S. Pat. No. 8,550,150 B2 describe LHP type heat transfer devices particularly applicable to computers.
In order to avoid damages to electronic equipment caused by heat cycles due to temperature variations, Variable Conductance Heat Pipes (VCHP) have been proposed with a non-condensable gas in an interior of the heat pipe. The non-condensable gas resides in passages adjacent to the condenser section. As the heat load from a heat source increases or as the evaporator temperature increases, the vapor pressure of the working fluid increases which forces the non-condensable gas to compress and expose more of the condenser area. The dense vapor of the working fluid can then reach the exposed condenser surface for vapor condensation. On the other hand, when the evaporator is at a low temperature, the volume of the non-condensable gas increases, thereby increasing the blocked part of the condenser. The working fluid has a low vapor pressure allowing the component to warm up before the heat is removed. Due to the low vapor pressure, a relatively high volumetric flow rate would be needed to achieve a given amount of heat transfer. This high vapor flow rate can in turn facilitate maintaining the heat source at a relatively constant temperature despite a variation in the heat pipe's operating temperature.
U.S. Patent Application Publication 2013/029936 A1 describes a VCHP including an example for a heat source of a 22° C. to 50° C. temperature range.
Applicants do not know any aircraft ice protection system based on the above mentioned two-phase thermal transport technology.
The ice protection systems used by the aeronautic industry are focused in maintaining the aircraft wet surfaces (mainly leading edges of lifting surfaces, engine air inlets and propeller leading edges) at high temperature to avoid the water accumulation and even to evaporate the water. Different technologies are used for ice protection systems in the aeronautic industry, including:                (i) Hot air systems. These systems have low efficiency (maximum around 40%) because the air must maintain very high temperature to heat the external surfaces.        (ii) Heated blanket systems. They have problems with erosion and electrical power distribution.        (iii) Antifreeze fluid systems based on glycol to protect wings and leading edges of propellers. The main disadvantage is the high quantity of fluid to be stored. These systems are very complicated and they have high energy requirements with a maintenance burden.        
Aeronautic ice protection systems using the above mentioned technologies are energy consuming systems.